Gluon - a gauge boson that mediates strong interaction among quarks.Gluon
In physics, gluons are the elementary particles which are responsible for the strong nuclear force. They bind quarks together to form protons and neutrons as well as other hadrons; their electric charge is zero, their spin is 1 and they are generally assumed to have zero mass. Gluons are ultimately responsible for the stability of atomic nuclei.

In quantum chromodynamics (QCD), today's accepted theory for the description of the strong nuclear force, gluons are exchanged when particles with a color charge interact. When two quarks exchange a gluon, their color charges change; the gluon carries an anti-color charge to compensate for the quark's old color charge, as well as the quark's new color charge. Since gluons thus carry a color charge themselves, they can also interact with other gluons, which makes the mathematical analysis of the strong nuclear force quite complicated and difficult. Even though there are theoretically nine unique color combinations for gluons (r-ar, r-ag, r-ab, g-ar, g-ag, g-ab, b-ar, b-ag, and b-ab), due to the subtleties of SU(3) symmetry there are only eight different gluons.

The first experimental traces of gluons were found in the early 1980s at the electron-positron-collider PETRA at the DESY in Hamburg, when evidence for a clear three-jet structure was found; the third jet was attributed to one of the produced quarks emitting a gluon.

Strong Interaction Force
It turns out that some particles (quarks and gluons) have a type of charge that isn't electromagnetic; rather, it is called color charge. The force between color-charged particles is very strong, earning it the name Strong Force. Because this force holds quarks together to form hadrons, its carrier particles are whimsically called gluons because they so successfully "glue" the quarks together.

Color ChargeQuarks and gluons are color-charged particles. Just as electrically-charged particles interact by exchanging photons, color-charged particles exchange gluons in strong interactions. In so doing, these color-charged particles are often "glued" together.

The main difference between strong and electromagnetic interactions is the fact that the strong force-carrier particles (the gluons) themselves carry color charge. Photons, on the other hand, have no color charge.

Two or more quarks close to each other rapidly exchange gluons, creating a very strong "color force field" binding the quarks together. There are three color charges, and three corresponding anti-color (complementary color) charges. Quarks constantly change their color charge as they exchange gluons with other quarks.

Each quark has one of the three color charges; and each anti-quark has one of the three complementary color charges. Gluons carry color/anti-color pairs (they don't necessary have to be the same color; i.e.. red / anti-blue gluons are legal). While there are 9 possible combinations of color/anti-color pairs, due to symmetry considerations one of these combinations is eliminated. A gluon can effectively carry one of eight possible color/anti-color combinations.

Quarks carry color__
Anti-quarks carry anti-color.Gluons carry color and anti-color.
(From the above three lines we can presume the quark is the syntropic third, the anti-quark is the entropic third while the gluon is the neutral third - as per Keely's concept of thirds.)

Quark Confinement
Color-charged particles cannot be found individually. For this reason, the color-charge quarks are confined in groups (hadrons) with other quarks. These composites are color neutral.

Not until the development of the Standard Model's theory of the strong interactions could physicists explain why the quarks combine only into baryons (three quark objects), and mesons? (quark-antiquark objects), but not, for example, four quark objects. Now we understand that only those combinations are color neutral. Particles such as ud or dd that cannot be combined into color-neutral states are never observed experimentally.

How does color charge work?Color charge is always conserved. Therefore, when a quark emits or absorbs a gluon, that quark's color must change in order to conserve color charge. For example, suppose a "red" quark changes into a "blue" quark and emits a "red/anti-blue" gluon. The net color is still "red."

Quarks emit and absorb gluons very frequently within a hadron, so there is no way to observe the color of an individual quark. Within a hadron, though, the color of the two quarks exchanging a gluon will change in a way that keeps the bound system in a color-neutral state, so it will stay observable.

Color-Force Field
The quarks in a given hadron madly exchange gluons. For this reason, physicists talk about the color-force field which consists of the gluons holding the bunch of quarks together.

If one of the quarks in a given hadron is pulled away from its neighbors, the color-force field "stretches" between that quark and its neighbors. In so doing, more and more energy is added to the color-force field as the quarks are pulled apart. At some point, it is energetically cheaper for the color-force field to "snap" into two new quarks. In so doing, energy is conserved because the energy of the color-force field is converted into the mass of the new quarks, and the color-force field can "relax" back to an unstretched state.

Quarks cannot exist individually because they must maintain a color-force field with other quarks. (From Wikipedia, the free encyclopedia.)